The present invention relates to the field of laboratory apparatus, especially that for preparing samples for chemical analysis and in particular to evaporator-condenser apparatus. Its object is a device for evaporation and condensation in a closed environment.
During qualitative and/or quantitative chemical characterisation, particularly of solid bodies, it is almost always necessary to prepare samples before carrying out the analysis proper which enables their composition to be determined.
A conventional preparation process in chemistry is known by the name xe2x80x9cwet processxe2x80x9d and involves dissolving the organic or mineral substances to be examined using suitable solvents or reagents in order to xe2x80x9creleasedxe2x80x9d the compounds which can be collected and measured in the physicochemical or isotopic measuring apparatus normally used (HPLC, NMR, IR spectrophotometry, atomic absorption, etc.).
For solid inorganic compounds, particularly concentrated and corrosive mineral reagents are generally used, such as strong acids or mixtures of strong acids, strong bases or mixtures of strong bases which, in addition, sometimes have to be heated.
As to the solvents normally used to dissolve organic compounds, these are often harmful, even toxic, to man and his environment.
The end result of dissolving the sample (and any subsequent chemical stages such as neutralisation, filtration, precipitation, solvent substitution, etc.) is therefore a liquid solution of a more or less large volume which has to be reduced in order to concentrate the xe2x80x9creleasedxe2x80x9d substances to be analysed. In some cases, it may even be necessary to remove completely the liquid or liquids used to prepare the sample to obtain what is known as a dry residue.
This concentration operation is conventionally carried out by heating said solution in a suitable receptacle and by evaporating the liquids or solvents under an extraction hood and/or by using evaporators. Known evaporators are, for example, evaporators supplied by a specific gaseous stream or rotating evaporators that allow at least a proportion of the evaporated solvents and reagents to be recovered and recycled.
However, evaporation in so-called xe2x80x9copenxe2x80x9d environments poses many problems with regard to safety and environmental protection. In deed, the vapours of the chemical solvents or reagents contained in the solutions to be concentrated are generally harmful to the health of the operator, to the equipment (pipes, filters, etc.), and even dangerous (risk of fire or explosion), In addition, ever stricter environmental standards entail putting in place complex devices to neutralise and filter the solvent-charged air sucked in by the hoods and/or the charged gases leaving gaseous stream evaporators before their discharge to the atmosphere.
In addition, the air or gases reaching the hood or gaseous stream evaporators risk contaminating the sample to be analysed, which may lead to subsequent erroneous measurements, particularly where detection of the presence of trace elements is concerned. In certain cases it may therefore be necessary to ensure that the entering air or gases are suited to the type of solution to be treated and/or are particularly pure, which is neither practical nor economic.
Although evaporators supplied by a specific gas stream prevent the dissemination of evaporated reagents in the extraction hood, using them is still a constraint in that it involves handling samples in sequence.
Rotating evaporators also have a number of drawbacks. They are relatively sophisticated, small in size, difficult to maintain, fragile when handled and, because of their complexity, relatively expensive. In addition, they are not suited to the evaporation of certain particularly corrosive inorganic reagents such as hydrofluoric acid, for example.
The object of the present invention in particular is to overcome these disadvantages.
To this end, it concerns a device for evaporation and condensation in a closed environment comprising essentially an evaporation receptacle, a heating means for said evaporation receptacle and a condensation receptacle connected in a substantially sealed manner to said evaporation receptacle, characterised in that said evaporation and condensation receptacles are connected to each other, at their openings, extending on either side of a common separation plane, in such a way that the arrangement of said receptacles forms substantially an inverted xe2x80x9cVxe2x80x9d with a sharp point and in that substantially the entire surface of the wall forming the evaporation receptacle is brought, by said heating means, to the same temperature T1 higher than the highest temperature T2 of the wall forming the condensation receptacle.